Background: Little is known about factors that influence home-based child care providers' participation in professional development. Factors that predict participation in activities that are designed to promote the utilization and maintenance of skills taught are of particular interest. Objective: Our aim was to examine factors in the home-based child care context that might influence participation in professional development, including demographic variables, working conditions, preintervention skills and training, perceptions of workshop usefulness, and interpersonal factors such as job-related stress and depressive symptoms. Methods: In this exploratory study, we examined predictors of participation among 67 home-based child care providers in Oregon, USA, who took part in the intervention group of a randomized efficacy study on a multiphase professional development program to promote preschoolers' positive social development. Results: Latent class analysis of participation resulted in three distinct groups: those who participated in the initial three workshops (WS), those who participated in workshops plus maintenance activities (consultation and a booster session, WS+), and those with little to no participation (NP). The NP group was too small to include in further analysis. A multivariate logistic regression model with child care provider education, number of preschool-age children enrolled in care, child-to-caregiver ratio, and self-reported stress included as predictors significantly improved classification in the WS+ group compared to the WS group. Conclusions: These findings offer a preliminary look at the unique factors influencing home-based child care providers' participation in extended professional development. Relevancy of content to child care providers' situations appears to be important.